Author Topic: DIY parting off tool for T-bar parting off blade?  (Read 11801 times)

Offline PekkaNF

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DIY parting off tool for T-bar parting off blade?
« on: September 09, 2013, 07:08:35 AM »
I have a QCTP and some parting tools including some GTN3 tools.

I bought some 12 mm high and 1,6 mm narow T-type parting off blades. I would like to build a holder for it.
http://www.eccentricengineering.com.au/index.php?page=shop.browse&category_id=23&option=com_virtuemart&Itemid=3&vmcchk=1&Itemid=3

There is a parting tool holder:
http://www.eccentricengineering.com.au/index.php?option=com_content&view=article&id=31&Itemid=45
But it has some features I don't desire. And too many moving parts when clampped into QC holder.

I envisioned something simple and now I have been drawing and designing a "perfect" holder that has no serious drawbacks my other HSS-blade holders have. More I think of more I'm going circles :scratch:

I'm very tempted to tilt the blade about 3 - 7 decrees to give some rake. Stupid or smart? Aloris does it. Also my standard QCTP has it:
http://www.arceurotrade.co.uk/catalogue/results.aspx?search=090-070-00504
I'm cutting mainly different grades of steels, ocassionally some stainles steed and tough materials. Hardly never brass or coper metals. I'm willing to dedicate different tools for aluminium.

I have seen some drawings and holders that hold blade nicely without too much protrusion. But this blade is pretty square on the bottom and top. Very tempted to slit saw an apropriate grove for the body of of the blade and just put square clamp on the top. Would it work?

I ahve made some toolshanks, booring tools and QC holders, but this is somewhat new venture. Any advice?

Thank you,
Pekka

Offline mechman48

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Re: DIY parting off tool for T-bar parting off blade?
« Reply #1 on: September 10, 2013, 06:35:46 AM »
Hi Pekka  :wave:
I have a blade of the same type that I had put away many moons ago, simply for the fact that with the limited amount of parting off I did the ordinary style blade sufficed so I forgot all about it until I saw your post. I'm sure a lot of us would be keen to see your holder, or even your drawing, & I'm sure that your idea of a slit groove would work without any trouble.  :headbang:

Cheers
George
George.


Always look on the bright side of life, & remember.. KISS..' Keep It Simple Stupid'

Offline bp

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Re: DIY parting off tool for T-bar parting off blade?
« Reply #2 on: September 11, 2013, 03:20:25 AM »
When I made my pillar and clamp on toolholder style QCTP, the parting toolholders looked like the attached picture (at least I hope it's attached!)  This was for a mini lathe, a Sieg C3, so it runs "backwards" ...clockwise looking from the tailstock.  They have worked very well, the blades are A. R. Warner 0.04" and 1/16" from LMS.  Routinely part off Al. Alloy at 800 or 900 rpm, steel at 400 rpm.
cheers
bp

Offline PekkaNF

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Re: DIY parting off tool for T-bar parting off blade?
« Reply #3 on: September 11, 2013, 07:28:05 AM »
Thank you.

May I ask few questions about this Bp tool-holder?

1) Judging from the last picture. Is there a little angle to keep the blade against the holder? If not, how well does the blade stays put? On quite a few design people have added some extra screws or camfered the blade and made mating surface.

2) What is the "rake" angle and how do you feel about it? Thank you on the material and rpm information.

I have some A. R. Warner HSS inserts and tool shanks. Like them. If you like Warner, you probably know also Mesa Tool (http://www.mesatool.com/)? Great place to shop. I specially like threading/grroving tools.

Pekka

Offline unc1esteve

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Re: DIY parting off tool for T-bar parting off blade?
« Reply #4 on: September 11, 2013, 10:49:00 AM »
I made a holder to match my QCTP following G H Thomas's design in The Model Engineers Workshop Manual.  I made mine with no angle.  Once the height is set to center the blade can be removed and sharpened and then returned to center with no further adjustment.  The angled design must be adjusted after each sharpening.

Offline bp

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Re: DIY parting off tool for T-bar parting off blade?
« Reply #5 on: September 12, 2013, 12:52:55 AM »
Hi PekkaNF,
1/  No the groove that holds the blade has square sides, you may notice that part of the groove is a little bit deeper to take the "T" piece.  When installing the blade the thinner part of the "T" is pushed home with finger pressure as the screws are nipped up.  It works very well and I have only had the blade come out when I was trying to find the limits, which were trying to take a normal longitudinal cut with a parting tool (!!)
2/  The angle which provides the rake is 5 degrees.  That seems to work well.

Yes I like the AR Warner stuff, I have quite a lot of their tooling.  Mainly I get it from Little Machine Shop, but I'll have a look at Mesa Tool!!
cheers
bp

Offline Arbalist

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Re: DIY parting off tool for T-bar parting off blade?
« Reply #6 on: January 10, 2015, 08:47:58 AM »
I'm also interested in making an upside down parting tool Pekka. Trouble is I bought two blades from Chronos and they are different heights as well as widths. Be nice to make a holder that takes both blades ideally.

The radiused T type blades are on this page. They were quite a bit cheaper than other places.

http://chronos.ltd.uk/acatalog/New--Clamp-Type-Parting-Tool-s-with-Chipbreaker-Blade--5--cobalt-.html

Offline Arbalist

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Re: DIY parting off tool for T-bar parting off blade?
« Reply #7 on: January 10, 2015, 07:46:21 PM »
I've just checked the centre height to tool post measurement and come up with a quick design. Should be simple enough to make if I have the stock.

Offline Arbalist

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Re: DIY parting off tool for T-bar parting off blade?
« Reply #8 on: January 12, 2015, 04:33:07 AM »
After a quick rummage I've found I don't have the material to make the main block in one piece. I've come up with a two piece design though plus clamp that should do the job.

Offline PekkaNF

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Re: DIY parting off tool for T-bar parting off blade?
« Reply #9 on: January 12, 2015, 04:47:59 AM »
How are you going to hold the blade?

I have't build that one yet, my GTN3 blade and inserts seem to work good enough, but it looks like a project to try out.

Pekka

Offline Arbalist

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Re: DIY parting off tool for T-bar parting off blade?
« Reply #10 on: January 12, 2015, 09:25:03 AM »